Prevalence of thermophilic campylobacter infections in humans, chickens and crows in Morogoro, Tanzania

Prevalence of thermophilic Campylobacter infections in humans, chickens and crows was determined in a cross-sectional study that was carried out in urban and rural areas of Morogoro region, Tanzania during the period of January 2003 to December 2004. A total of 632 human stool samples, 536 cloacal swabs from local and broiler chickens and 22 intestinal contents from crows were screened for presence of thermophilic campylobacters using Skirrow's protocol. Representative Campylobacter jejuni isolates from human and chicken samples were also analysed by polymerase chain reaction (PCR) as a definitive identification method. The overall prevalence of thermophilic campylobacters was 9.3% (95% CI: 7.2-11.9), 69.8% (95% CI: 65.7-73.6) and 72.7% (95% CI: 49.8-89.3) in humans, chickens and crows respectively. In humans, 59 thermophilic campylobacters were isolated of which 96.6% were C. jejuni and 3.4%Campylobacter coli. There was a significantly (P<0.001) higher prevalence in young individuals (16%) than in adults (7%). Of 341 isolates from chickens, 91.2% were C. jejuni and 8.8% were C. coli. A significantly (P<0.05) higher infection rate was observed in rural local chicken (76%) than in broilers (60%). In crows, of 16 isolates, 93.8% were C. jejuni and 6.2% were C. coli. Definitive identification of C. jejuni by PCR revealed positive results in 74.1% of 243 analysed isolates. Findings in this study indicate high prevalence of thermophilic campylobacters in humans, chickens and crows in Morogoro, and a higher infection rate of C. jejuni than that of C. coli in different animal species. Age of humans and location of chickens were identified as risk factors for thermophilic Campylobacter infections. Positive isolates to biochemical tests that indicated negative results on PCR indicates the additional value of PCR for definitive diagnosis of C. jejuni.     

Genotypic characterisation and cluster analysis of Campylobacter jejuni isolates from domestic pets, human clinical cases and retail food

The genetic similarity of Campylobacter jejuni isolates from pets, compared to human clinical cases and retail food isolates collected in Ireland over 2001-2006 was investigated by cluster analysis of pulsed-field gel electrophoresis (PFGE) fingerprinting profiles. Comparison of the PFGE profiles of 60 pet isolates and 109 human isolates revealed that seven (4.1%) profiles were grouped in clusters including at least one human and one pet C. jejuni isolate. In total six (1.6%) of 60 pet and 310 food profiles were in clusters with at least one food and one pet C. jejuni isolate. The detection of only a small number of genetically indistinguishable isolates by PFGE profile cluster analysis from pets and from humans with enteritis in this study suggests that pets are unlikely to be an important reservoir for human campylobacteriosis in Ireland. However, genetically indistinguishable isolates were detected and C. jejuni from pets may circulate and may contribute to clinical infections in humans. In addition, contaminated food fed to pets may be a potential source of Campylobacter infection in pets, which may subsequently pose a risk to humans.     

Effect of dietary supplementation with selenium-enriched yeast or sodium selenite on selenium tissue distribution and meat quality in beef cattle

The objective was to determine the concentration of total Se and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in postmortem tissues of beef cattle offered diets containing graded additions of selenized enriched yeast (SY; Saccharomyces cerevisiae CNCM I-3060) or sodium selenite (SS). Oxidative stability and tissue glutathione peroxidase (GSH-Px) activity of edible muscle tissue were assessed 10 d postmortem. Thirty-two beef cattle were offered, for a period of 112 d, a total mixed ration that had been supplemented with SY (0, 0.15, or 0.35 mg of Se/kg of DM) or SS (0.15 mg of Se/kg of DM). At enrollment (0 d) and at 28, 56, 84, and 112 d following enrollment, blood samples were taken for Se and Se species determination, as well as whole blood GSH-Px activity. At the end of the study beef cattle were killed and samples of heart, liver, kidney, and skeletal muscle (LM and psoas major) were retained for Se and Se species determination. Tissue GSH-Px activity and thiobarbituric acid reactive substances were determined in skeletal muscle tissue (LM only). The incorporation into the diet of ascending concentrations of Se as SY increased whole blood total Se and the proportion of total Se comprised as SeMet, as well as GSH-Px activity. There was also a dose-dependent response to the graded addition of SY on total Se and proportion of total Se as SeMet in all tissues and GSH-Px activity in skeletal muscle tissue. Furthermore, total Se concentration of whole blood and tissues was greater in those animals offered SY when compared with those receiving a comparable dose of SS, indicating an improvement in Se availability and tissue Se retention. Likewise, GSH-Px activity in whole blood and LM was greater in those animals offered SY when compared with those receiving a comparable dose of SS. However, these increases in tissue total Se and GSH-Px activity appeared to have little or no effect in meat oxidative stability.     

现代种业科企合作模式探索实践与成效——以重庆三峡农业科学院为例

近年来,特别是国家种业"新政"出台后,面对种业发展新挑战,重庆三峡农业科学院积极尝试与种企建立战略合作伙伴关系,取得了显著成效。文章阐述了重庆三峡农业科学院在健全激励机制、加强植物品种和知识产权保护等方面的主要做法和取得的成效,探索了科企合作模式,如自行实施、许可实施、转让实施、合作实施和代育品种等,以期进一步完善科企合作、产研融合的双赢发展新机制。     

灰色关联度分析在玉米品种评价中的应用

采用灰色关联度分析法,对2005年重庆市玉米区域试验平丘A组中的9个参试品种(组合)的13个性状进行了分析。综合评价结果表明,沈鸿一号综合性状最好(r=0.873 1),华试301(r=0.862 6)、沈鸿三号(r=0.791 0)综合性状较差。     

两种方法对几个玉米自交系遗传特性及育种潜势的比较分析

试验采用7个自选系、7个外引系、外杂选系和按NCⅡ组配的49个杂种F1组合为研究材料.应用混合线性模型、配合力两种分析方法对单株粒重的遗传方差和遗传力的分析结果进行了比较,并在此基础上对LUP两种效应值与两种配合力效应值进行了比较分析.结果表明:混合模型分析只揭示了显性和加加上位性效应;而配合力分析是在加-显遗传模型基础上进行的,只能揭示加性和显性效应.两种分析方法所得各遗传方差分量与遗传力都基本一致.分析LUP所预测的单株粒重的各遗传效应值表明:LUP加性效应各亲本系列(包括亲本效应)与一般配合力大小顺序完全一致;LUP的显性效应与各组合的特殊配合力及超对照优势均呈极显著的正相关关系(r=0.70和r=0.93),特殊配合力与超对照杂种优势的相关系数(r=0.56)也达到极显著水平。     

Attenuation of low-frequency sound in freshwater

Lake Superior was chosen as an experimental site to compare sound absorption of freshwater with the results of absorption measurements in seawater. The relaxation-like absorption at 1 kilohertz occurring in seawater is also present in freshwater. A relaxation related to the structural characteristics rather than to the salt content of water may be responsible for the anomalous absorption.     

Cow-level evaluation of a kinetics ELISA with multiple cutoff values to detect fecal shedding of Mycobacterium avium subspecies paratuberculosis in New York State dairy cows

In control programs for Mycobacterium avium subsp. paratuberculosis (Map), the infection status of the cows in a herd is often obtained by testing (a sample of) the herd with an ELISA that may lack some sensitivity and specificity but that is fast and inexpensive. In New York State (NYS), an unabsorbed kinetics ELISA (KELA) has been used extensively for Map control. The objective of this study was to determine the relative sensitivity and specificity of the KELA for detection of fecal shedding of Map for the NYS dairy cow population, taking into account possible confounders such as different antigen batches and Map prevalence in a herd.

The data for the study consisted of all serum samples from NYS dairy cows with concurrent fecal culture results submitted to the NY Animal Health Diagnostic Laboratory (NYAHDL) between 1991 and 1996 (n = 10,562). The data represented cows with different levels of fecal shedding from herds with different within-herd Map prevalence, including herds that were whole herd fecal culture negative on repeated testing.

The cutoff values were based on the predictive value for fecal shedding obtained with a multiple logistic regression model that included variables for the three antigen batches and the Map prevalence in the herd. The KELA could not distinguish between non-shedders and low shedders (≤30 total colony forming units (TCFU)) and thus the predictive value of the KELA to detect moderate to heavy fecal shedders (>30 TCFU) was modeled. The three cutoff values of 65, 135 and 170 were based on low (<0.2), moderate (<0.80) and high (>0.95) probabilities for moderate to heavy fecal shedding. The sensitivity and specificity values relative to culture were 67% and 95.2%, 31% and 99.7%, and 11% and 99.9% for the three cutoff values, respectively. Cutoff values for the KELA decreased for herds with increasing within-herd Map prevalence. For the best positive predictive value of a KELA for moderate to heavy fecal shedding, the cutoff values should be determined based on the apparent within-herd prevalence in a herd.     

Efficacy and safety of selamectin against gastrointestinal nematodes in cats presented as veterinary patients

A series of randomized, controlled, masked, field (veterinary patient) studies were conducted in the USA and Europe to evaluate the efficacy of selamectin, a novel macrocyclic lactone of the avermectin subclass, in the treatment of naturally acquired gastrointestinal nematode infections in cats. After confirmation of ascarid and/or hookworm infection, 298 cats of various ages and breeds were randomly assigned to treatment with selamectin (n=202) or an existing commercially approved positive-control product (n=96). Unit doses of selamectin (providing a minimum dosage of 6mgkg(-1)) were administered topically to the skin in a single spot at monthly intervals. Quantitative fecal examinations were performed on days 0 (before treatment), 30, and 60. In the selamectin-treated cats, fecal ascarid egg counts were reduced by 99.6 to 100% on day 30, and by 99.9 to 100% on day 60. Fecal hookworm egg counts were reduced by 98.3% on day 30, and by 100% on day 60 in the selamectin-treated cats. The positive-control products achieved reductions in egg counts of 96.5 to 100% (ascarids) and 98.9 to 99.9% (hookworms). These studies have shown that monthly topical administration of selamectin is safe and highly effective in the treatment of naturally acquired ascarid and hookworm infections in cats.